Electronic devices commonly use electromagnetic interference (EMI) shielding to prevent disruption of their performance resulting from electromagnetic fields present in the operating environment. Some electronic devices incorporate a metal container or “can” that surrounds the electronic device to form an electromagnetic shield, which is electrically connected to a ground in the device. This shield attenuates the EMI field before it reaches the device. Other EMI isolation systems use metal plates that fit over board-mounted electronic devices. Packaged electronic devices that include an integrated circuit (IC), such as a ball grid array (BGA) electronic package, may include on the package a metal film deposited by sputtering or chemical vapor deposition (CVD). This metal film is electrically connected to a ground conductor layer, such as extending under the IC to a wall of the package, to isolate the IC from electromagnetic interference.
In another example, conductive paint that has metal particles suspended in a fluidic carrier is sprayed onto the exterior surface of the electronics package, for example, a ball grid array package. The sprayed conductive paint is cured to remove the fluidic carrier, leaving a metal film coated to the outside of the electronic package. Grooves are cut into the surface, such as in the encapsulation material, to expose the conductive paint to a ground conductor circuit located at a ground conductor layer. This system may require a ground conductor layer in the package that extends to the package perimeter. Other EMI shielding systems for electronic packages use wire bonding from the IC to a shield layer on the package. These techniques may increase manufacturing complexity and raise costs.